/Engine/Plugins/Runtime/GameplayAbilities/Source/GameplayAbilities/Public/GameplayEffect.h
Update a set-by-caller magnitude for the active effect to match the new value, if possible
void UpdateActiveGameplayEffectSetByCallerMagnitude ( [FActiveGameplayEffectHandle](API\Plugins\GameplayAbilities\FActiveGameplayEffectHandle) ActiveHandle, const [FGameplayTag](API\Runtime\GameplayTags\FGameplayTag) & SetByCallerTag, float NewValue )